As a system for efficiently performing data communication in wireless communication, for example, Japanese Patent Application Laid-open Publication NO. 2002-354010 discloses a device in which, upon starting hand-over for a wireless data communication device switching base stations, a retransmission timer is paused so that unnecessary packet retransmission can be avoided.
However, in wireless communication, not only hand-over for switching base stations, there are many other factors bringing about changes in a communication environment. For example, while a wireless communication device is moving, the number of other communication devices in its vicinity may be increasing, causing congestion in wireless communication, or radio shielding may exist in the area where the device is getting in, weakening the strength of radio-signal to be received. A wireless communication device is required to keep efficient communication even in such a changeable communication environment.